Composite



Patented Apr. 12, 1921.

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QR R w & W wm ATTORNEY UNITED STATES .HAROLD S. OSBORNE, OF NEWYORK, N. Y., ASSIGNOR T0 AMERICAN TELEPHONE ANDTELEGRAPII COMPANY, A CORPORATION OF NEW YORK.

Application filed February 12, 1919. Serial No. 276,487.

To an whom it may concern: 7

Be it known that I, HAuoLn S. Oseonnn, residing at New York, in the county of New York and State of New York, have invented certain Improvements in Composite PhantomGircuits, of which the following is a specification. y

This invention relates to signaling sys tems, and-particularly those in which tele phone and telegraphic communication are had over the same conductors.

The inventionis related to that disclosed. in copcnding applicationSerial No. 266,326, filed December 11, 1918, in which provision. is made for using complete metallic telegraph circuits co-incide11tffor themost part with the telephone circuits, and employing smallteiegraphic currents the same order of magnitude as the telephone currents. One object of the present invention is to provide for both side circuit and phantom circuit transmission of the telegraph signals in one my channels. Another object is to provide system of high pass and low pass filters for separating the telephone and telegraph. currents in such a system.

The invention willbe more fully desfcribed 1n connection with the accompanying drawing'in whlch the single figure illustrates diagrammatically a system embodying this in vention.

Two metallic circuits 1 and 2 are here shown as constituting the side circuits for telephone. transmission, and these are connected to produce a phantom circuit for telephone communication in the usual way by leads tapped off at the central po'intsof the transformers 3. These telephone channels may beeither one way or two way circuits. If they are one way circuits they will, ordinari'ly though. not necessarily, be combined with other one waycircuits to form what is known as a four wire circuit, or the equivalent, so that communication in either direction may be had.

Telegraphic sending apparatus may be lo cated at one end of the transmission line, and telegraphic receiving apparatus at the other, as shown in the drawing, the intention being in this case to use the circuits for one way transmission only for telegraphic purposes. A sending set 4 is bridged across each of the circuits 1 and 2, and comprises a single source of current 5 connected to a pole changer 6. In the form shown, the pole Specification of Letters Patent.

COMPOSITE PHANTOM CIRCUITS.

Patented Apr. 12, 1921.

changer consists of a pair of arms moving in unlson and connected to the opposite poles of the current source. These are arranged to vibrate between contacts connected to. the conductors which bridge the circults" 1 and 2, each conductor running to a contact associated with each arm and lying on opposite sides of the respective arms so that themovementof thearms from one side to the other will reverse the current in a well-known manner. It will be, under :stood, that any known form of pole changer may be used. It may. be desirable in some cases however, that the polechangerbe arranged as shown to have make-before-break contact so that the circuit is never actually opened; and to prevent the current source from being short circuited when the pole changer is at rest, it may then be biased to one position by a spring, as indicated in the drawing, and operated in the other direction by a magnet under the control of the telegraph key, Obviously however, other biasing means such as an ordinary polarized relay maybe employed, if desired. The re- "sistancefcustomarily employed in series with here representedgby a simple magnet 16, it

being'understood that any suitable receiving lnstrument may be used, provided the windings thereof are so disposed that they afford mid or neutral points 17 for those relays which are connected immediately across the respective side circuits 1 and 2. The phantom receiving relay is connected between the neutral points of the side circuit relays as indicated on the drawing.

For separating the telephone and telegraph currents at either end ofthe line is an arrangement of properly tuned filter circuits of a general character now wel1-known in the art. For the arrangement of circuits here shown, the high pass filter for the side telephone circuits may consist of a capacity 7 provided with itsown low pass filter, consisting of inductaiices 13in series with the line, and capacities 14 in shunt thereto, and the phantom telegraph branch has its individual low pass filter composed of similarly arranged inductances "and capacities "13 and 1%, located in the leads running to the central points 8 in the side circuit apparatus. i

At'the receiving end of the system, low

pass filters 15 and 15 are arranged in the side and phantom. telegraph circuits and high pass filters 18 and 18 in the side and phantom telephone circuits in the same manner as justdescribed for the transmitting end. These filters may be of the same construction as the corresponding'filters at the sending end, though it is not usually neces sary that they be composed of as many sections. At the sending end, the filters must serve not only to prevent the shunting of the telephone currents, but must prevent the higher harmonics, resulting from the operationof the sending instruments, from reaching the telephone instruments. At the receiving end, this latter function is not required of the filters, and in many instances one section will be sufficient.

It is to. be understood that the invention is not limitedto the details herein described, since it is obviousthat many modifications may be made within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed is: v j 1. In a signaling system, the combination of two pairs of line conductors, telephone apparatus connected to said conductors to provide two side circuits and one phantom circuit, telegraph apparatus bridged across each pair of conductors forming one of said side circuits, said apparatus including a sending set whose elements are arranged to provide a mid or neutral point with respect to the side circuit conductors, and other telegraph apparatus connected between said neutral points.

2. In a signaling system, the combination of two pairs of line conductors, telephone apparatus connected to said line conductors to provide two side circuits and one phantom circuit, telegraph sending apparatus connected across each side circuit and ineluding a single source of current and a pole changer for reversing its relation to the conductors leading to said side circuit, a mid or neutral point in each of said sources of current and other telegraph sending apparatus connected between said mid or neutral points.

3. In a signaling system, two pairs of line conductors, telephone apparatus connected to said pairs of line conductors to form two side circuits and one phantom circuit, telegraph apparatus connected for oneway transmission to said pairs of conductors to form two side circuits and one phantom circuit, high pass filters respectively individual to said side and phantom circuits connected in the branches leading to the telephone apparatus, low pass filters respectively individual to the side and phantom telegraph circuits connected in the branches leading to the tranmitting and receiving ends of said circuits, the filters in the receiving end of said telegraph circuit having constants designed for the separation of the relatively weak received currents, and the filters at the transmitting end of said telegraph circuits having constants designed to prevent the relatively strong transmitted impulses from entering the telephone branches of the circuit and to suppress the higher harmonics of the transmitted impulses sufiiciently to prevent interference with the telephone transmission.

Intestimony whereof I have signed my name to this specification this tenth day of February, 1919.

HAROLD S. OSBORNE. 

